Two years ago, Joe Harrow's most impressive management experience was a job as camp director for two summers. Today, he leads Groupon's 300-person customer-service department and is responsible for disseminating the Groupon gospel to 700 additional customer-service employees across the world.

"My closest thing to customer-service experience was working at a coffee shop in college," he told me. But 29-year-old Mr. Harrow has been with Groupon from the beginning. He knew the product well and when customers started calling, he picked up the phone. When there were too many calls for him to answer alone, he started hiring.

Mr. Harrow's now-massive team is testament to Groupon's decidedly old-fashioned approach to business. While other internet sensations such as Google and Facebook have developed self-service technology to get at the small business long-tail, the latest digital darling is focusing on service with a smile, phone calls and manpower.